What is anorectal cancer?

Anorectal melanoma is a rare cancer that starts in the anus or rectum (back passage). It can happen at any age but is more likely to affect people over the age of 60.

Anorectal melanoma is also called anorectal mucosal melanoma (ARMM).

We have separate information about:

Symptoms of anorectal melanoma

Possible symptoms include:

  • bleeding from the back passage – this is the most common symptom
  • pain or itching in the back passage
  • a lump in the back passage
  • a lump or swelling in the groin
  • a change in your bowel habits (diarrhoea, constipation or incontinence)
  • feeling the urge to pass a bowel motion, even though the bowel is empty.

These symptoms can be caused by many other conditions. But it is very important to have them checked by your GP.

Causes of anorectal melanoma

The causes of anorectal melanoma are not known. The main cause of skin melanoma is UV light from sunlight and sunbeds. But this is not a risk factor for anorectal melanoma.

Diagnosis of melanoma

You will usually begin by seeing your GP, who will examine you. They will give you a rectal examination. This is where your doctor will feel for any lumps or swelling by putting a gloved finger into your back passage (rectum).

If your GP is not sure what the problem is, or thinks your symptoms may be linked to cancer, they will refer you to a hospital specialist.

At the hospital, the specialist doctor will ask you about your symptoms and general health. You will then have some further examinations:

  • You will have another rectal examination.
  • Women may have an internal examination of the vagina.
  • The doctor will also feel your groin to check whether the lymph nodes are swollen.
  • The doctor will also arrange for you to have a biopsy – this is when the doctor removes a small piece of tissue to be checked for cancer cells.

Waiting for tests results can be a difficult time, we have more information that can help.

Further tests

You may also have other tests to check whether the cancer has spread.

  • CT scan

    A CT (computerised tomography) scan uses x-rays to build a three-dimensional (3D) picture of the inside of the body.

  • MRI (magnetic resonance imaging) scan

    An MRI scan uses magnetism to build up a detailed picture of areas of your body.

  • PET-CT scan

    A PET-CT scan is a combination of a CT scan, which takes a series of x-rays to build up a 3D picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

  • Ultrasound scan (ultrasound of the groin)

    An ultrasound scan uses sound waves to make up a picture of a particular area of the body. It is a painless test and only takes a few minutes. Once you are in a comfortable position, a gel is spread over the groin. A small device like a microphone, which produces sound waves, is then passed over the groin. This produces a picture on a screen.

  • Rectal ultrasound scan

    For a rectal ultrasound, you lie on your side with your knees bent. A nurse or doctor gently passes a small, lubricated probe, which produces sound waves, into your back passage. The test takes about 30 minutes.

  • Fine needle aspiration (FNA) of the lymph nodes

    If the ultrasound shows that the lymph nodes are larger than normal, the doctor will do a fine needle aspiration of the node or nodes. The doctor passes a fine needle into the lymph node and withdraws (aspirates) some cells into a syringe.

Stages of anorectal melanoma

The stage of a cancer describes its size and how far it has spread, based on your test results.

You and your doctors can then talk about the best treatment choices for you.

Treatment for anorectal melanoma

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your doctor will explain the different treatments and their side effects. They will also talk to you about the things you should consider when making treatment decisions.

The main treatment for anorectal melanoma is surgery.

Sometimes other treatments, may be given to reduce the risk of the cancer coming back after surgery. Or you may have treatment to manage the symptoms of cancer that has spread. These treatments include:

  • Radiotherapy

    Radiotherapy uses high-energy rays to destroy the cancer cells. Radiotherapy given to this part of the body is called pelvic radiotherapy.

  • Targeted therapies

    Targeted therapies are drugs that target the differences between cancer cells and normal cells. There are several targeted therapies used to treat melanoma. These include ipilimumab and imatinib. Some targeted therapy drugs only work if the cancer has changes in genes called BRAF and c-KIT. Your doctor may talk to you about this type of treatment if surgery is not possible or if the cancer comes back. This treatment may only be available if you take part in a clinical trial.

You may be given your treatment as part of a clinical trial.

After anorectal melanoma treatment

Follow-up care after treatment

The aim of follow-up care is to make sure everything is going well and to find out if you have any concerns. The appointments are usually every few months in the first year.

We have more information on follow-up care after treatment.

Well-being and recovery

Even if you already have a healthy lifestyle, you may choose to make some positive changes after treatment. We have more information on leading a healthy lifestyle after treatment.

How we can help

Macmillan Grants

If you have cancer, you may be able to get a Macmillan Grant to help with the extra costs of cancer. Find out who can apply and how to access our grants.

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